Tb_chapter25

Chapter 25, Optical Instruments C HAPTER 25 Conceptual Questions C1. Using a camera with a fixed focal length lens, how will decreasing the f-number affect the depth of field and the intensity of the light reaching the ccd (or film)? a. The depth of field will increase as will the intensity of light reaching the ccd. b. The depth of field will increase but the intensity of light reaching the ccd will decrease. c. The depth of field will decrease as will the intensity of light reaching the ccd. d. The depth of field will decrease but the intensity of light reaching the ccd will increase. C2. A person can see well in the distance, but cannot do so at an arm’s-length distance. To correct this, lenses that are _________ having a ________ power could be used. a. thicker at their center than at the edges, positive b. thicker at their center than at the edges, negative c. thinner at their center than at the edges, positive d. thinner at their center than at the edges, negative C3. The eye parts iris, retina, cornea, and ciliary muscle, play roles related to _________, ________, _________, and _________ in a camera. a. the aperture, the lens, the ccd, focusing b. the aperture, the ccd, the lens, focusing c. the lens, the aperture, focusing, the ccd d. the lens, focusing, the ccd, the aperture C4. A magnifying lens of power d (in diopters) gives what magnification when the viewing eye is relaxed assuming a near point of 25 cm? a. 25d b. 0.25/d c. d/4 d. The correct answer is not given. C5. Why is it easier to see fine print in brighter light than in dimmer light? a. This is not so, it is easier to see fine print in dimmer light than in brighter light. b. Because the power (in diopters) of the eye increases as the light intensity increases. c. In brighter light, the longer wavelengths dominate. d. In brighter light, the f-number of the eye increases. 173

25.1 The Camera 1. What is the f-number of a camera lens that has an aperture-opening diameter of 0.30 cm and a focal length of 3.0 cm? a. 0.10 b. 0.80 c. 10 d. 15 2. A camera lens is initially set at f /16 for a shutter speed of 1/60 s. If the amount of lighting on the subject is unchanged, and the lens is set at f /5.6, what is the proper shutter speed at this setting? a. 1/500 s b. 1/250 s c. 1/8 s d. 1/16 s 3. Tripling the aperture diameter of a camera lens will change the f-number by what factor? a. 1/9 b. 1/3 c. 3 d. 9 4. Tripling the focal length in a telephoto lens, while keeping the aperture size constant, will change the f-number by what factor? a. 1/9 b. 1/3 c. 3 d. 9 5. Doubling the aperture diameter of a camera lens will change the light intensity admitted to the film by what factor? a. 0.25

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